1. Field of the Invention
The present invention relates generally to data communications and more specifically to an apparatus and a system for efficient encoding of out of order data packets in a network, such as, for example, a wireless communication network.
2. Background
In recent years, two communication technologies have seen a significant increase in demand. The Internet, with its subset, the World Wide Web (WWW), has seen tremendous increase in usage, even resulting in network capacity issues and, thus, reduced performance of traditional applications. Wireless telephony, also known as cellular telephony, has provided its users with reasonable quality of service and convenient features.
As traditional wireless communication systems are designed for voice communications, new Internet applications, such as, for example, real-time interactive audio/video communications, introduce new challenges and demand improved quality of service parameters. One of these challenges involves conservation of bandwidth and, specifically, the large header overhead associated with transmission of data units of transmission and reception, also known as data packets.
Data packets arrive at a source unit, such as, for example a base station or a Packet Data Serving Node (PDSN), and travel between the source unit and a destination unit, such as, for example, a mobile station, through communication links, such as, for example, wireless (cellular) links. Prior to transmission to the destination unit, the header information stored within each data packet is further compressed at the source unit using one of many known compression algorithms, such as, for example, an algorithm described in detail in “Robust Header Compression (ROHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed,” by C. Borman et al., July 2001. Network Working Group, codified as RFC 3095. At the destination, the header information is decompressed and is attached to its corresponding payload to re-form the original data packet.
During transmission and/or reception within the wireless communication system, and prior to arrival at the source unit, certain data packets are lost and/or misplaced. The misplaced data packets eventually reenter the data stream, but their header field information is inconsistent with the rest of the data packets in the stream. As a result, during compression and subsequent decompression of the header information, additional bandwidth is required to identify and transmit such out of order data packets to the destination unit. Alternatively, if the data packets are misplaced between the source unit and the destination unit, the packets may be dropped due to inconsistency and decoding calculation failure.
Since the proposed header compression algorithms do not appear to handle out of order data packets efficiently and do not accomplish an adequate reduction of bandwidth consumption for such packets, there is a need for a robust header compression algorithm able to handle such misordered data packets in a network.